Method of and apparatus for producing x rays



July 13 1926. 1,592,348

, D. D. EVI NS METHOD OF AND APPARATUS FOR PRODUCING X RAYS Filed May 23, 1925 Patented July 13, 1926.

UNITED STATES ossa D. nvms, or DAvENroa'r, IOWA.

)iETHOD OF AND APPARATUS FOR PRODUCING X RAYS.

Application filed May 23, 1925'. Serial No. 32,261.

My invention relates to a process of and an apparatus for producing X-rays. It has for its particular object the production of uniform or undamped rays in which the shorter oscillations are substantially ehminated. Other objects will appear from time to timein the course of the specification and claims.

I illustrate my invention more or less diagrammatically in the accompanying drawings wherein Figure 1 is a diagrammatic illustration. of

- my apparatus;

Figure 2 is a diagrammatic illustration of the:1 rays produced by prevailing methods; an

Figure 3 is a diagrammatic illustration of the waves produced by my new method or apparatus.

Like parts are illustrated by like symbols throughout the specification and drawings.

Referring to .Fi re 1, A is the usual X-ray tube with the cathode A and the anti-cathode or target A".

The lines B B extend from the opposite terminals of the tube to the opposite ends of the secondary induction coil C which consists of fine wire wound about the hollow tube C apart and in practice I find that 200turns of fine wire form a practical coil. D is a variable condenser across the lines B B Coiled about the oil C is the primary induction coil E which may be formed of from two to four turns of heavy wire. From one end of the primary coil leads the line E through the battery or other power source E to the. plate E of the electron tube E The line E leads from the opposite end of the primary coil E to the grid E of the tube. The filament E is in circuit with the battery E and the rheostat' The individual coils are spaced cuits more or'less variant from the one illustrated might be employed without departing from the spirit of my invention. The use and operation of my invention are as follows:

One of the problems in Xray work is the provision of a current of uniform oscillation: or wave length; 5 Heretofore has prevailed the use of alternating current stepped up through a transformer, which produced what are enerallyknown as damped oscillations. he nature of these damped waves is diagrammatically illustrated in Figure 2, the wave dying down from a maximum to zero, with a break between the mlnimum osclllatlon and the 1111- 'tial oscillation of the succeeding wave.

Each such group of diminishing oscillations and uniformity of oscillation, each oscillation being of the same length and character as the next. I am able by my method to produce such an oscillation and to obtain a far evener penetration than has heretofore been obtained and to eleminate almost entirely the uneven oscillation and the soft rays which cause the burning. The few remaining soft rays are almost entirely due to reflection or glancing of rays striking opaque objects.

In my method I employ the usual radio A and B batteries and the usual circuits one of which includes the electron tube filament. the A battery and a variable resistance and the other including the plate, the grid, and the B battery. I insert in the grid plate circuit a primary induction coil of a small number of loops of relatively heavy wire and shunt the coil across to the filament circuit intermediate its ends. Within the heavy primary coil I position a secondary fine wire coil of a larger number of turns, 200 being a fear example. The B battery delivers to the primary coil a current of constant or uniform sQiHatiOn which is,

stepped up to high frequency and delivered at high frequency to the X-ray tube. The variable condenser permits tuning.

W'here I have illustrated as a source of supply for the Tesla coil a battery suc-h as is used in radio circuit, the current of which passes through plate and grid, I might employ other sources of energy.

The current delivered to the X-ray tube by the secondary coil is uniform and the rays projected by the tube are undamped and even. A fair illustrative parallel is the difference between Waves sent out by the old Wireless circuit transmitters and the present electron tube transmitters.

I claim:

1. In an X-ray projector, and circuit therefor, an electron tube comprising 'filament, grid and plate, a grid-platc circuit, a primary induction coil in *said circuit, a

power source "in said circuit, a filament circuit, a power source in said filament circuit, a connection between said filament circuit and said coil, intermediate the ends of said coil, a variable resistance in said filament circuit, a high frequency secondary coil Within said primary induction coil, an X-ray tube in circuit with said secondary coil, and a variable condenser across said circuit.

-2. In an Xu-ay projector an electron tube, a filament circuit therefor, a grid-plate circuit therefor, a primary induction coil in circuit witlrsaid grid-plate circuit a secondary coil associated therewith and an X-ray tube in circuit with said secondary coil.

3. In an X-ray projector, an electron tube comprising filament, grid and plate, a gridplate circuit, a primary induction coil in said circuit, an electric power source in said circuit, a filament circuit, a secondary coil within said primary induction coil, an X- ray tube in circuit with said secondary-coil.

4. In an X-ray projector and circuit therefor, a primary induction coil, a secondary coil, an X-ray tube in circuit with saidsecondary coil, a tuning means across said coil and means for .said secondary X-ray tube circuit, an electron tube in circuit with the primary coil, and a source of electric energy in said circuit.

5. In an X-ray projector and circuit therefor, a primary induction coil, a secondary coil, an X-ray tube in circuit with said secondary coil, a variable condenser across said X ray tube .circuit, an electrontube in circuit with the primary coil, and a source of electric energy in said circuit.

6. In an X-ray projector and circuit therefor, a primary induction coil, a secondary coil, an X-ray tube in circuit with said secondary coil, atuning means across said X-ray tube circuit, an electron tube in circuit with the primary coil, a source of electric energy interposed in the gridplate circuit, .a filament circuit and a source of energy interposed therein.

7. In an 'X-ray' projector and circuit therefor, a primary induction 'co'il,a lsecondary coil, an X-ray tube in circuit with said secondary --coil, a tuning means across said X-ray tube circuit, an electron tube in circuit with the primary coil, a sourceof electric energy interposed in the grid-plate circuit, a filament circuit and a source of energy interposed therein, and a shunt connection between the filament-circuit and the primary coil.

8. In an X-ray projector and circuit therefor, a primary induction coil, a secondary coil, an X-ray tube in circuit with said secondary, coil, means for passing a pulsating current through said primary tuning the tube circuit.

9. In an X-ray projector and circuit therefor, a primary induction coil and a secondar-y coil, an X-ray tube in circuit with coil, means for passing a pulsating current through .saidprimary coil and tuning means for bringing resonance in the inducing and the induced circuits.

Signed atChicago, --county of (900k and State of Illinois, this 6th-da1y of May, 1 925.

DQSSA I). EVINS, 

